1. Field
This disclosure relates to transmitting and receiving the state of electrical signals via a point-to-point radio frequency link; more specifically to radio-based cable replacement systems.
2. Background Art
Industrial facilities often have sensors and controllers that are remote from a central monitoring and control station. This can be in power plants, petroleum, and chemical operations as well as many others. Typically, long electrical cables convey the signals between remote locations and a control room. There are now many devices known that reduce the amount and length of cabling by using a network, particularly a radio frequency based network, to convey signals. In these systems a device at one end receives several electrical inputs, determines their states and transmits the state information to a distant unit. The distant unit receives the data, and based on it, sets its several outputs to correspond to the state of the first unit's inputs, thereby acting as a cable replacement. Signals can be from the field to a control room, from a control room to a remote location, or otherwise at a distance from each other. Many of these systems are susceptible to issues and disadvantages including complexity of configuration, unpredictable latencies, single points of failure, and difficulty in diagnosing problems.
Some of those issues and disadvantages are radio interference, failure in the firmware or hardware of the end-point devices, network failure, and loss of power to the devices. Inevitably some degree of increased latency is also introduced.
Other disadvantages can include ease of configuration. While running a long cable can be challenging in some locations, there is no configuration involved other than determining which conductor at one end corresponds to which conductor at the other end. In contrast, radio-frequency network-based cable replacement systems usually require downloading software from the manufacturer's web site, using a computer in the field to download settings to each unit, and many more steps. While growing in use, these systems can benefit from simpler configuration and more robust and diagnosable radio linkages.